The actual biochemical block in the arg-2 mutant of Chlamydomonas reinhardi

Abstract

Arg-2, one of the first arginine-requiring mutants isolated in Chlamydomonas reinhardi, has long been regarded as lacking the enzyme argininosuccinate synthetase. In view of various discrepancies found in the literature, the position of this mutant has been reviewed. The results show that arg-2 has a normal argininosuccinate synthetase activity but lacks argininosuccinate lyase. This finding is in agreement with the results of recombination and complementation analysis, which indicate that arg-2 is included in the arg-7 cistron.